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July 19, 1932. KARQLUS Re. 18,537

RECEIVER ARRANGEMENT FOR ELECTRIC TELEVISION APPARATUS Original Filed Aug. 31. 1926 INVENTOR AUGUST KAROLUS ATTORNEY Reissued July 19, 1932 UNITED STATES PATENT. OFFICE I AUGUST RULES, OF LEIPZIG', GERMANY, ASSIGNOR TO GORPURATIOI' 0]! AMERICA, A CORPORATION OF DELAWARE RECEIVER ARRANGEMENT FOR ELEG'ERIC TELEVISION APPARATUS (trig-inst No. 1,762,231, dated- Iune 10, 1930, Serial No, 1:32,?02, filed. August 31,v 1926, and in Germany September 5, 1925r Application for reissue: filed September 23, 19301. Serial No- 483,960.

My invention relates to a receiver arrange ment for electric television apparatus and has for its objects simplification of the optical arrangement and greater brightness of a the television image.

A. television apparatus usually comprises a source of light, a light relay by which the light radiated from the sourceis regulated in accordance with therelative brightness of i the several areas of the image transmitted by the sender, means for coordinating the areas so transmitted and which constitute the image, said means operating in synchronism with the means at the senderfor breaking up the image, and optical auxiliaries. v

Heretofore the general arrangement ofthe principal parts constitutinga receiver was such that the light from the light source was first regulated asto its brightness by the light relay and then directed to the coordinating means which projected the image into a single plane or on a suitable screen for observation. e

In contradistinction to this known ar- "J rangement, in my invention the light is directed onto the screen or the image plane as radiated from the light source, that is with. out previous regulation as to brightness and the image is then viewed through the medi- "i um of the lighting. relay which is arranged into the complete image serves for directing the light rays issuing from the several dots in the illuminated plane into the light relay and into the observers eye, or theentire radiation of light from the source is concentrated and directed on the image plane by the area coordinator.

In this novel arrangementofparts in the receiver only that portion of the light radiation which is projected into the eye at: a

given time is varied as to its: brightness, in

contradistinction to the existing arrangement in which the entire radiation from the source of light had to pass the light relay.

The advantages of the novel arrangement are particularly important where electricall'y controlled relays are provided the operation. of which is based on the known electrooptical or magneto optical efl'ect' on polarized light. Effects whichmay he applied in the present instance are principally The Fara da'y. efl'ect-in which the rotation of the pa la'rizationplane of the light is utilized by a magnetic field; the Kerr phenomenon, rotation of the olarization plane ofvv the light during the. refihctionl at a magnetized mirror; and the Kerr efi' ect, electrical double refraction in a condenser. filled with a suitable transparent medium. A very suitable lightrelay for television apparatus is the Kerr cell on account of its lack of inertia and its quantitative effect due to which. it may" he used for the highest frequencies; However, its load is limited to a predetermined maximum quantity oflight and therefore this maximum Wasa limit for the intensity of the source of light with the ahove-mentioned arrangement 0t parts since the total quantity of light ra diated from the source had to pass the Kerr cell and only a fraction of this quantity got into the eye of the observer.

In myn'ovel arrangement, on the I other hand it is possible to increase theintensity of the source of light to such an extent that the fraction of its light which is projected into the observers eye, is at the limit ofi load. for the Kerr cell. Therefore, the brightness of the image Will'be much higher than in the known arrangements.

The arrangement according to my inven t'ion involves the further advantage ofa considerahle simplification of the optical. auxiliaries. For instance if a Kerr cell is usedlin; connection with the known arrangements it is necessary to provide systems oflenses parallelizing. the rays of the bundle of light I which system is dispensed with in my novel arrangement according to my invention. as the eye is enabled to survey the entire plane of the image through the Kerr cell directly.

Figs-3 illustrates an apparatus where-the light rays are concentrated. and directed across the field of the image. a

' Referring'now to Figs. 1 and 2, 1 is a source of light,'2 is a'lens through which the light 7 ofthe source is concentrated, and 3 is a plate on which'the concentrated light is projected; The plate 3may be of any suitable construe; tion, for instance, it may be the known Nip,- kow'perforated plate which serves for breaking up the image at the sender and is'here utilized at thereceiver for-coordinating the transmitted areas into a complete image. light relay, for instance 2. Kerr cell 4, may be arranged on the side of the plate 3 which is opposite the source of light 1, and 5 is the eyeof the observer who surveys through the lightrelay that part of the plate 3 which constitutes the image field. A ray of light which passes through one of the perforations 3 10f the plate? is projectedintothe eye 5 through the'Kerr cell 4 in which its intensity is regulated. Only this fraction of the radiation and not the totalquantity oflight radiated from the source 1,.passes through the Kerr cell 4.

f Referringnow to Fig. 3,, the source of light, the light relay, which maybe a Kerr-cell, and the eye 0f the observer areindicated by the same reference numerals as in Figs. 1

and 2 but in this case the light from thev source 1" whichmay be either an arc 'lamp'or a glow lamp is directed onto two mirrors 6 and 7, which may, for instance, be arranged to pivotor oscillatein two planes at'right' angles to each other, for instance by arranging the mirror 6 to oscillate about the vertical axis and to reflecta light beam therefrom to the mirror 7 arranged to pivot or oscillate about a horizontal axisso as to direct theraysof light onto thes creen 8 along two coordinates at right angles to each other. The focus 'point 11 upon the picture screen 8, due'to the motion of the mirrors 6 and 7 travels over the entire surface in the shape of a relatively narrow zigzag line. The travelling or migration of this luminous spot of concentrated brightness is viewed through the light control cell4 through the eye 5, and it is only by reason of the fact that the permeability of the cell 4 is controlled by the incoming current that a picture is producedin the-eye. The advantage of this arrangement that intensity control means inserted-in the path of the rays between 1 and 11 may even be dispensed with according to this inven-' tion; It will be understood that this intensity controlling device would produce an lmpairing action on account of the lossof light 1 incidentally produced thereby.

I wish it to be understood that I do-not desire to be limited to the exact details of construction shown and described for obvious modifications such as are suggested by my copending-application Serial No. 322,7 56, filed November 30, 1928, disclosing purely electrical means for positioning a light spot on a screen, will occur to a person skilled in the art, and I, therefore, believe myself to be entitled to make and use any and all of these modificationsasfall fairly within the spirit and scope of thehereinafter appended claims.

I claim 1. A receiver for electric televisionlapparatus including a light relay of the Kerr type, comprising, a light screen, a source of luminous rays, means for projecting said luminous rays as a position controlled point source of light upon said screen, and a light relay interposed between an observer and said screen whereby said observer when looking through said light relay toward said screen may view a series of position controlled light spots and visually construct a moving image upon said screen. 'j-' v 2. A receiver arrangement for electric television apparatus 7 comprising, a source of light, a picture point distributor, anoptical system including a plurality of oscillating mirrors foriill'uminating said distributor and moving concentrated light beams from said light source back and forth across said distributor surface in synchronism with a corresponding motion at a transmitting station, and a light relay positioned between an observer and said distributor, said relay being controlledvby variations in received signal eluding a light source, a distributor screen,

means positioned between said light source and said distributor screen for directing light as a point source to said screen and moving the light point with respect thereto, and a light relay positioned between an observer and said distributor screen, said light relay being subjected to variations in potential in accordance with signal pulses, whereby an relay receives an optical impression of light images produced by said variations in potential applied to said relay and corresponding to a like image at a point of transmission.

4:. A receiver for electric television apparatus including a light relay of the Kerr type comprising a screen, a source of rays for pro ducing a light spot upon said screen, means for projecting said rays as a position controlled point source upon said screen for producing light at different elemental areas thereof, and a light relay interposed between an observer and said screen whereby said observer when looking through said light relay toward said screen may view a series of position controlled light spots and visually construct a moving image upon said screen.

5. An apparatus for electric television including a distributor screen, a source of rays for producing a luminous effect upon said screen, means positioned between said source and said distributor screen for directing said rays as a point source upon said screen and moving the light point produced by said rays acting upon said screen with respect thereto, and a light relay positioned between an observer and said distributor screen, said light relay being subjected to variations in potential in accordance with signal pulses, whereby an observer viewing said screen through said relay receives an optical impression of light images produced by said variations in potential supplied to said relay corresponding to a like image at a point of transmission.

6. A television receiving system for electrooptically forming images at a receivin point of an object at a transmitting point comprising means for successively illuminating with equal intensity the elemental areas of a screen, a light valve for directly viewing said screen,

and means for controlling the light valve by incoming image current, so as to cause the illumination of each elemental area of said screen when viewed through said light valve to assume an observable intensity corresponding to the intensity of light and shadow on coordinated elemental areas of an object at a transmitter.

7. A television receiving system comprising means for causing the elemental areas of a field to become illuminated with equal intensity light in the same sequence as the corresponding portions of the field of View at the transmitter are scanned, said light being of the same intensity for each elemental area for directly viewing said light field from a point lying within all of said angles and at such a distance from said field that only a "small part of the light therefrom enters said valve, and means for controlling said light valve by incoming image currents. observer vlewlng said screen through said "8. A television receiving system comprisinga light field in the form of a stationary screen, means for causing light spots to appear at each elemental area of the screen in the same sequence as the corresponding portions of the field of view at the transmitter are scanned, said light being of the same intensity for each elemental area and radiating with substantially the same intensity throughout a wide solid angle, a light valve for viewing said screen from a point lying within allof said angles and at such a distance from said screen that only a small part of the light enters said light valve, and means for controlling said light valve by incoming image currents.

9. The method of television which comprises causin a light spot to appear at each elemental area of a field in the same sequence as the corresponding areas of the field of view at the transmitter are scanned, said light spots being of the same intensity for each elemental area and radiating with about the same intensity throughout a wide solid angle, viewing said light field from a point lying within all of said angles and at a distance from said light field, and controlling in accordance with the incoming image current and substantially at the observing point the amount of light entering the eye of the observer by means of a light valve, whereby the valve controls only a small fraction of the emitted light.

10. A television receiving system comprising a receiving screen, means for causing the elemental areas of said screen to become illuminated in a predetermined sequence with light spots of the same intensity, a Kerr cell through which only a small part of the light from each of said elemental areas passes, and means to control said cell in accordance with variations in received image current.

11. In a television system, means for predeterminedly. and uniformly causing a point of illumination to traverse an image plane, and means between said point and a second image plane for electrically eclipsing the light to produce the effectsof variations in intensity of light and shadow on the first image plane.

12.. In a television system, a viewing screen,

means for causing each elemental area of the 1 screen to become illuminated at each elemental area thereof with light of equal intensity along predetermined paths of recurring traversals, an electro-responsive light valve between an observer and the screen through my name this 9th which the lightspots on the screen are observed, and a means to control the electrorresponsive valve so that the light viewed by the observer through the valve is of controlled 5 value and representative of variations inintensity of light and shadow on elemental points of the subject of which an image is belng produced. e

In witness whereof I hereunto subscribe day of September, 1930;

AUGUST KABOLUS. 

